1. Field of the Invention
This invention relates to the puncturing device designed particularly for puncturing patient's skin in order to collect a blood sample for diagnostic purposes.
2. Description of the Related Art
The U.S. Pat. No. 5,356,420 discloses a puncturing device comprising a sleeve and a push element positioned at the first end of the sleeve. The other end of the sleeve ends with a bottom with an opening therein. Inside the sleeve a piston is slidably mounted, terminating with a push rod at the end closer to the push button, and with a puncturing tip at the end closer to the bottom opening. Inside the sleeve between the push element face and the piston, a drive spring is located, and between the piston and the sleeve bottom a return spring is placed. The piston comprises wings located on its outer perimeter which rest on an internal projection of the sleeve.
Further, the U.S. Pat. No. 5,439,473 discloses a lancet designed for puncturing patient's skin for the sake of collecting small blood samples. The lancet has elongated housing, wherein a movable member is disposed sliding along the housing axis, while the housing has a top opening for the lancet push button, and a bottom opening for the piercing blade. The movable member consists of a flat spring, one end of which is linked to the push button. The push button has two upper arms perpendicular to its surface, and those arms have hooked ends disposed in oblong openings of the housing side walls. The other end of the movable member flat spring is joined with a holder wherein the piercing blade is fixed. The holder lower portion has two lower arms parallel to the upper arms. The lower arms have moreover upwardly directed, triangle shaped tips, which rest upon the lower edges of the oblong openings of the housing walls. All parts of the movable member are made of plastics.
When the patient's skin is being punctured, the lancet press button is pressed, by what the flat spring of the movable member is tensed, and hooked ends of the upper arms press against the tips of the lower arms of the movable member. Next the release of the lower arms occurs, the flat spring rebounds, and the patient's skin is punctured by the piercing blade which passes through the housing bottom opening. After puncturing the flat spring assumes free position, and the piercing blade retracts inside the lancet housing.
Further, the U.S. Pat. No. 5,755,733 discloses a lancet device consisting of a lancet assembly and a holder linked to the lancet assembly, wherein the lancet assembly has a lancet with piercing portion, and an ejector which pushes the lancet out. In the known lancet device the lancet piercing portion is covered with plastic material.